Being Alone, Less Social Increases Lifespan Of These Squirrels

Humans, since we evolved into the earliest Homo ancestors and maybe even before that, are social creatures, an attribute exploited ruthlessly by social networking platforms. And being social does us some good too, notably by having a positive correlation with how long we live.

The more social among us tend to live longer, and significantly so. A meta-analysis of almost 150 studies, covering over 300,000 individuals, in 2010 showed a clear advantage for humans who were relatively more social. “By the time half of a hypothetical sample of 100 people has died, there will be five more people alive with stronger social relationships than people with weaker social relationships,” according to that study.

But what is true for humans is not necessarily true for other living beings. And in this case, it is certainly not true when it comes to yellow-bellied marmots, a type of large ground squirrel. If anything, it is the opposite, a new study found.

It must be noted that marmots are not nearly as inherently social as humans generally are. Some individuals live alone, while others live in groups that comprise of between six and 24 adults — mostly females — and their offspring. The males usually leave the groups.

Daniel Blumstein, a professor at University of California, Los Angeles, led the long-term study of 66 adult female marmots who were observed from 2002 to 2015 in the Rocky Mountain Biological Laboratory, Colorado. His team found less social marmots to live two years longer than the more social ones, on average. For a lifespan that lasts 14-15 years on the upper side, that is quite a significant difference.

“More social marmots are less likely to survive over the winter, and they live shorter lives, on average. We’re finding costs for adult female marmots to be nice to other female marmots. This species of marmots is not highly social, and for them, it seems costly to interact with others. … Females that are too nice don’t live as long and have fewer offspring each year,” Blumstein said in a statement Wednesday.

Being social could be detrimental to marmots for a number of reasons, he explained. For instance, it could increase the risk of contracting a disease or being infected by a parasite, like fleas (this happened with humans a number of times in the past, and still happens). Or it could increase competition for food during times when their dietary sources are already scarce.

Given the contrast with humans, whose social relationships help reduce other stresses in life, does this study have any relevance to us? If we are considering individuals who are not inherently very social, maybe so. At any rate, studying a non-social species may tell us something new.

“Being social has benefits, but we’re finding costs of being too social. By studying a species that doesn’t want to be social, we are finding insights we wouldn’t have found by studying social primates,” Blumstein said in the statement.

The open-access study, titled “Strong social relationships are associated with decreased longevity in a facultatively social mammal,” appeared online Wednesday in the journal Proceedings of the Royal Society B.